Fluid ejection chip that incorporates wall-mounted actuators

ABSTRACT

A fluid ejection chip includes a substrate. A plurality of nozzle arrangements is positioned on the substrate. Each nozzle arrangement includes a nozzle chamber defining structure which defines a nozzle chamber and which includes a wall in which a fluid ejection port is defined. Each nozzle arrangement includes at least one actuator for ejecting fluid from the nozzle chamber through the fluid ejection port. The, or each, actuator is displaceable with respect to the substrate on receipt of an electrical signal. The, or each, actuator is formed in said wall of the nozzle chamber defining structure, so that displacement of the, or each, actuator results in a change in volume of the nozzle chamber so that fluid is ejected from the fluid ejection port.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation application U.S. application Ser. No. 09/855,093 filed May 14, 2001, now U.S. Pat. No. 6,505,912, which is a Continuation Application of U.S. application Ser. No. 09/112,806, filed Jul. 10, 1998, now granted U.S. Pat. No. 6,247,790.

The following Australian provisional patent applications are hereby incorporated by cross-reference. For the purposes of location and identification, US patents/patent applications identified by their US patent/patent application serial numbers are listed alongside the Australian applications from which the US patents/patent applications claim the right of priority.

Cross- U.S. Patent/ Referenced Patent Application Australian (Claiming Right Provisional of Priority from Patent Australian Provisional Application No. Application) Docket No. PO7991 6750901 ART01US PO8505 6476863 ART02US PO7988 6788336 ART03US PO9395 6322181 ART04US PO8017 6597817 ART06US PO8014 6227648 ART07US PO8025 6727948 ART08US PO8032 6690419 ART09US PO7999 6727951 ART10US PO8030 6196541 ART13US PO7997 6195150 ART15US PO7979 6362868 ART16US PO7978 6831681 ART18US PO7982 6331669 ART19US PO7989 6362869 ART20US PO8019 6472052 ART21US PO7980 6356715 ART22US PO8018 6894694 ART24US PO7938 6636216 ART25US PO8016 6366693 ART26US PO8024 6329990 ART27US PO7939 6459495 ART29US PO8501 6137500 ART30US PO8500 6690416 ART31US PO7987 7050143 ART32US PO8022 6398328 ART33US PO8497 7110024 ART34US PO8020 6431704 ART38US PO8504 6879341 ART42US PO8000 6415054 ART43US PO7934 6665454 ART45US PO7990 6542645 ART46US PO8499 6486886 ART47US PO8502 6381361 ART48US PO7981 6317192 ART50US PO7986 6850274 ART51US PO7983 09/113054 ART52US PO8026 6646757 ART53US PO8028 6624848 ART56US PO9394 6357135 ART57US PO9397 6271931 ART59US PO9398 6353772 ART60US PO9399 6106147 ART61US PO9400 6665008 ART62US PO9401 6304291 ART63US PO9403 6305770 ART65US PO9405 6289262 ART66US PP0959 6315200 ART68US PP1397 6217165 ART69US PP2370 6786420 DOT0US1 PO8003 6350023 Fluid01US PO8005 6318849 Fluid02US PO8066 6227652 IJ01US PO8072 6213588 IJ02US PO8040 6213589 IJ03US PO8071 6231163 IJ04US PO8047 6247795 IJ05US PO8035 6394581 IJ06US PO8044 6244691 IJ07US PO8063 6257704 IJ08US PO9057 6416168 IJ09US PO8056 6220694 IJ10US PO8069 6257705 IJ11US PO8049 6247794 IJ12US PO8036 6234610 IJ13US PO8048 6247793 IJ14US PO8070 6264306 IJ15US PO8067 6241342 IJ16US PO8001 6247792 IJ17US PO8038 6264307 IJ18US PO8033 6254220 IJ19US PO8002 6234611 IJ20US PO8068 6302528 IJ21US PO8062 6283582 IJ22US PO8034 6239821 IJ23US PO8039 6338547 IJ24US PO8041 6247796 IJ25US PO8004 6557977 IJ26US PO8037 6390603 IJ27US PO8043 6362843 IJ028US PO8042 6293653 IJ29US PO8064 6312107 IJ30US PO9389 6227653 IJ31US PO9391 6234609 IJ32US PP0888 6238040 IJ33US PP0891 6188415 IJ34US PP0890 6227654 IJ35US PP0873 6209989 IJ36US PP0993 6247791 IJ37US PP0890 6336710 IJ38US PP1398 6217153 IJ39US PP2592 6416167 IJ40US PP2593 6243113 IJ41US PP3991 6283581 IJ42US PP3987 6247790 IJ43US PP3985 6260953 IJ44US PP3983 6267469 IJ45US PO7935 6224780 IJM01US PO7936 6235212 IJM02US PO7937 6280643 IJM03US PO8061 6284147 IJM04US PO8054 6214244 IJM05US PO8065 6071750 IJM06US PO8055 6267905 IJM07US PO8053 6251298 IJM08US PO8078 6258285 IJM09US PO7933 6225138 IJM10US PO7950 6241904 IJM11US PO7949 6299786 IJM12US PO8060 6866789 IJM13US PO8059 6231773 IJM14US PO8073 6190931 IJM15US PO8076 6248249 IJM16US PO8075 6290862 IJM17US PO8079 6241906 IJM18US PO8050 6565762 IJM19US PO8052 6241905 IJM20US PO7948 6451216 IJM21US PO7951 6231772 IJM22US PO8074 6274056 IJM23US PO7941 6290861 IJM24US PO8077 6248248 IJM25US PO8058 6306671 IJM26US PO8051 6331258 IJM27US PO8045 6110754 IJM28US PO7952 6294101 IJM29US PO8046 6416679 IJM30US PO9390 6264849 IJM31US PO9392 6254793 IJM32US PP0889 6235211 IJM35US PP0887 6491833 IJM36US PP0882 6264850 IJM37US PP0874 6258284 IJM38US PP1396 6312615 IJM39US PP3989 6228668 IJM40US PP2591 6180427 IJM41US PP3990 6171875 IJM42US PP3986 6267904 IJM43US PP3984 6245247 IJM44US PP3982 6315914 IJM45US PP0895 6231148 IR01US PP0869 6293658 IR04US PP0887 6614560 IR05US PP0885 6238033 IR06US PP0884 63120760 IR10US PP0886 6238111 IR12US PP0877 6378970 IR16US PP0878 6196739 IR17US PP0883 6270182 IR19US PP0880 6152619 IR20US PO8006 6087638 MEMS02US PO8007 6340222 MEMS03US PO8010 6041600 MEMS05US PO8011 6299300 MEMS06US PO7947 6067797 MEMS07US PO7944 6286935 MEMS09US PO7946 6044646 MEMS10US PP0894 6382769 MEMS13US

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

The present invention relates to the field of fluid ejection and, in particular, discloses a fluid ejection chip.

BACKGROUND OF THE INVENTION

Many different types of printing mechanisms have been invented, a large number of which are presently in use. The known forms of printers have a variety of methods for marking the print media with a relevant marking media. Commonly used forms of printing include offset printing, laser printing and copying devices, dot matrix type impact printers, thermal paper printers, film recorders, thermal wax printers, dye sublimation printers and ink jet printers both of the drop on demand and continuous flow type. Each type of printer has its own advantages and problems when considering cost, speed, quality, reliability, simplicity of construction and operation etc.

In recent years the field of ink jet printing, wherein each individual pixel of ink is derived from one or more ink nozzles, has become increasingly popular primarily due to its inexpensive and versatile nature.

Many different techniques of ink jet printing have been invented. For a survey of the field, reference is made to an article by J Moore, “Non-Impact Printing: Introduction and Historical Perspective”, Output Hard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988).

Ink Jet printers themselves come in many different forms. The utilization of a continuous stream of ink in ink jet printing appears to date back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hansell discloses a simple form of continuous stream electro-static ink jet printing.

U.S. Pat. No. 3,596,275 by Sweet also discloses a process of a continuous ink jet printing including a step wherein the ink jet stream is modulated by a high frequency electro-static field so as to cause drop separation. This technique is still utilized by several manufacturers including Elmjet and Scitex (see also U.S. Pat. No. 3,373,437 by Sweet et al).

Piezoelectric ink jet printers are also one form of commonly utilized ink jet printing device. Piezoelectric systems are disclosed by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which utilizes a diaphragm mode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) which discloses a squeeze mode form of operation of a piezoelectric crystal, Stemme in U.S. Pat. No. 3,747,120 (1972) which discloses a bend mode of piezoelectric operation, Howkins in U.S. Pat. No. 4,459,601 which discloses a piezoelectric push mode actuation of the ink jet stream and Fischbeck in U.S. Pat. No. 4,584,590 which discloses a shear mode type of piezoelectric transducer element.

Recently, thermal ink jet printing has become an extremely popular form of ink jet printing. The ink jet printing techniques include those disclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S. Pat. No. 4,490,728. Both the aforementioned references disclose ink jet printing techniques which rely on the activation of an electrothermal actuator which results in the creation of a bubble in a constricted space, such as a nozzle, which thereby causes the ejection of ink from an aperture connected to the confined space onto a relevant print media. Manufacturers such as Canon and Hewlett Packard manufacture printing devices utilizing the electro-thermal actuator.

As can be seen from the foregoing, many different types of printing technologies are available. Ideally, a printing technology should have a number of desirable attributes. These include inexpensive construction and operation, high-speed operation, safe and continuous long-term operation etc. Each technology may have its own advantages and disadvantages in the areas of cost, speed, quality, reliability, power usage, simplicity of construction and operation, durability and consumables.

Applicant has developed a substantial amount of technology in the field of micro-electromechanical inkjet printing. The parent application is indeed directed to a particular aspect in this field. In this application, the Applicant has applied the technology to the more general field of fluid ejection.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, there is provided a nozzle arrangement for an ink jet printhead, the arrangement comprising a nozzle chamber defined in a wafer substrate for the storage of ink to be ejected; an ink ejection port having a rim formed on one wall of the chamber; and a series of actuators attached to the wafer substrate, and forming a portion of the wall of the nozzle chamber adjacent the rim, the actuator paddles further being actuated in unison so as to eject ink from the nozzle chamber via the ink ejection nozzle.

The actuators can include a surface which bends inwards away from the center of the nozzle chamber upon actuation. The actuators are preferably actuated by means of a thermal actuator device. The thermal actuator device may comprise a conductive resistive heating element encased within a material having a high coefficient of thermal expansion. The element can be serpentine to allow for substantially unhindered expansion of the material. The actuators are preferably arranged radially around the nozzle rim.

The actuators can form a membrane between the nozzle chamber and an external atmosphere of the arrangement and the actuators bend away from the external atmosphere to cause an increase in pressure within the nozzle chamber thereby initiating a consequential ejection of ink from the nozzle chamber. The actuators can bend away from a central axis of the nozzle chamber.

The nozzle arrangement can be formed on the wafer substrate utilizing micro-electromechanical techniques and further can comprise an ink supply channel in communication with the nozzle chamber. The ink supply channel may be etched through the wafer. The nozzle arrangement may include a series of struts which support the nozzle rim.

The arrangement can be formed adjacent to neighbouring arrangements so as to form a pagewidth printhead.

In this application, the invention extends to a fluid ejection chip that comprises

a substrate; and

a plurality of nozzle arrangements positioned on the substrate, each nozzle arrangement comprising

-   -   a nozzle chamber defining structure which defines a nozzle         chamber and which includes a wall in which a fluid ejection port         is defined; and     -   at least one actuator for ejecting fluid from the nozzle chamber         through the fluid ejection port, the, or each, actuator being         displaceable with respect to the substrate on receipt of an         electrical signal, wherein     -   the, or each, actuator is formed in said wall of the nozzle         chamber defining structure, so that displacement of the, or         each, actuator results in a change in volume of the nozzle         chamber so that fluid is ejected from the fluid ejection port.

Each nozzle arrangement may include a plurality of actuators, each actuator including an actuating portion and a paddle positioned on the actuating portion, the actuating portion being anchored to the substrate and being displaceable on receipt of an electrical signal to displace the paddle, in turn, the paddles and the wall being substantially coplanar and the actuating portions being configured so that, upon receipt of said electrical signal, the actuating portions displace the paddles into the nozzle chamber to reduce a volume of the nozzle chamber, thereby ejecting fluid from the fluid ejection port.

A periphery of each paddle may be shaped to define a fluidic seal when the nozzle chamber is filled with fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

FIGS. 1-3 are schematic sectional views illustrating the operational principles of the preferred embodiment;

FIG. 4( a) and FIG. 4( b) are again schematic sections illustrating the operational principles of the thermal actuator device;

FIG. 5 is a side perspective view, partly in section, of a single nozzle arrangement constructed in accordance with the preferred embodiments;

FIGS. 6-13 are side perspective views, partly in section, illustrating the manufacturing steps of the preferred embodiments;

FIG. 14 illustrates an array of ink jet nozzles formed in accordance with the manufacturing procedures of the preferred embodiment;

FIG. 15 provides a legend of the materials indicated in FIGS. 16 to 23; and

FIG. 16 to FIG. 23 illustrate sectional views of the manufacturing steps in one form of construction of a nozzle arrangement in accordance with the invention.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

In the following description, reference is made to the ejection of ink for application to ink jet printing. However, it will readily be appreciated that the present application can be applied to any situation where fluid ejection is required.

In the preferred embodiment, ink is ejected out of a nozzle chamber via an ink ejection port using a series of radially positioned thermal actuator devices that are arranged about the ink ejection port and are activated to pressurize the ink within the nozzle chamber thereby causing the ejection of ink through the ejection port.

Turning now to FIGS. 1, 2 and 3, there is illustrated the basic operational principles of the preferred embodiment. FIG. 1 illustrates a single nozzle arrangement 1 in its quiescent state. The arrangement 1 includes a nozzle chamber 2 which is normally filled with ink so as to form a meniscus 3 in an ink ejection port 4. The nozzle chamber 2 is formed within a wafer 5. The nozzle chamber 2 is supplied with ink via an ink supply channel 6 which is etched through the wafer 5 with a highly isotropic plasma etching system. A suitable etcher can be the Advance Silicon Etch (ASE) system available from Surface Technology Systems of the United Kingdom.

A top of the nozzle arrangement 1 includes a series of radially positioned actuators 8, 9. These actuators comprise a polytetrafluoroethylene (PTFE) layer and an internal serpentine copper core 17. Upon heating of the copper core 17, the surrounding PTFE expands rapidly resulting in a generally downward movement of the actuators 8, 9. Hence, when it is desired to eject ink from the ink ejection port 4, a current is passed through the actuators 8, 9 which results in them bending generally downwards as illustrated in FIG. 2. The downward bending movement of the actuators 8, 9 results in a substantial increase in pressure within the nozzle chamber 2. The increase in pressure in the nozzle chamber 2 results in an expansion of the meniscus 3 as illustrated in FIG. 2.

The actuators 8, 9 are activated only briefly and subsequently deactivated. Consequently, the situation is as illustrated in FIG. 3 with the actuators 8, 9 returning to their original positions. This results in a general inflow of ink back into the nozzle chamber 2 and a necking and breaking of the meniscus 3 resulting in the ejection of a drop 12. The necking and breaking of the meniscus 3 is a consequence of the forward momentum of the ink associated with drop 12 and the backward pressure experienced as a result of the return of the actuators 8, 9 to their original positions. The return of the actuators 8,9 also results in a general inflow of ink from the channel 6 as a result of surface tension effects and, eventually, the state returns to the quiescent position as illustrated in FIG. 1.

FIGS. 4( a) and 4(b) illustrate the principle of operation of the thermal actuator. The thermal actuator is preferably constructed from a material 14 having a high coefficient of thermal expansion. Embedded within the material 14 are a series of heater elements 15 which can be a series of conductive elements designed to carry a current. The conductive elements 15 are heated by passing a current through the elements 15 with the heating resulting in a general increase in temperature in the area around the heating elements 15. The position of the elements 15 is such that uneven heating of the material 14 occurs. The uneven increase in temperature causes a corresponding uneven expansion of the material 14. Hence, as illustrated in FIG. 4( b), the PTFE is bent generally in the direction shown.

In FIG. 5, there is illustrated a side perspective view of one embodiment of a nozzle arrangement constructed in accordance with the principles previously outlined. The nozzle chamber 2 is formed with an isotropic surface etch of the wafer 5. The wafer 5 can include a CMOS layer including all the required power and drive circuits. Further, the actuators 8, 9 each have a leaf or petal formation which extends towards a nozzle rim 28 defining the ejection port 4. The normally inner end of each leaf or petal formation is displaceable with respect to the nozzle rim 28. Each activator 8, 9 has an internal copper core 17 defining the element 15. The core 17 winds in a serpentine manner to provide for substantially unhindered expansion of the actuators 8, 9. The operation of the actuators 8, 9 is as illustrated in FIG. 4( a) and FIG. 4( b) such that, upon activation, the actuators 8 bend as previously described resulting in a displacement of each petal formation away from the nozzle rim 28 and into the nozzle chamber 2. The ink supply channel 6 can be created via a deep silicon back edge of the wafer 5 utilizing a plasma etcher or the like. The copper or aluminum core 17 can provide a complete circuit. A central arm 18 which can include both metal and PTFE portions provides the main structural support for the actuators 8, 9.

Turning now to FIG. 6 to FIG. 13, one form of manufacture of the nozzle arrangement 1 in accordance with the principles of the preferred embodiment is shown. The nozzle arrangement 1 is preferably manufactured using micro-electromechanical (MEMS) techniques and can include the following construction techniques:

As shown initially in FIG. 6, the initial processing starting material is a standard semi-conductor wafer 20 having a complete CMOS level 21 to a first level of metal. The first level of metal includes portions 22 which are utilized for providing power to the thermal actuators 8, 9.

The first step, as illustrated in FIG. 7, is to etch a nozzle region down to the silicon wafer 20 utilizing an appropriate mask.

Next, as illustrated in FIG. 8, a 2 μm layer of polytetrafluoroethylene (PTFE) is deposited and etched so as to define vias 24 for interconnecting multiple levels.

Next, as illustrated in FIG. 9, the second level metal layer is deposited, masked and etched to define a heater structure 25. The heater structure 25 includes via 26 interconnected with a lower aluminum layer.

Next, as illustrated in FIG. 10, a further 2 μm layer of PTFE is deposited and etched to the depth of 1 μm utilizing a nozzle rim mask to define the nozzle rim 28 in addition to ink flow guide rails 29 which generally restrain any wicking along the surface of the PTFE layer. The guide rails 29 surround small thin slots and, as such, surface tension effects are a lot higher around these slots which in turn results in minimal outflow of ink during operation.

Next, as illustrated in FIG. 11, the PTFE is etched utilizing a nozzle and actuator mask to define a port portion 30 and slots 31 and 32.

Next, as illustrated in FIG. 12, the wafer is crystallographically etched on a <111> plane utilizing a standard crystallographic etchant such as KOH. The etching forms a chamber 33, directly below the port portion 30.

In FIG. 13, the ink supply channel 34 can be etched from the back of the wafer utilizing a highly anisotropic etcher such as the STS etcher from Silicon Technology Systems of United Kingdom. An array of ink jet nozzles can be formed simultaneously with a portion of an array 36 being illustrated in FIG. 14. A portion of the printhead is formed simultaneously and diced by the STS etching process. The array 36 shown provides for four column printing with each separate column attached to a different color ink supply channel being supplied from the back of the wafer. Bond pads 37 provide for electrical control of the ejection mechanism.

In this manner, large pagewidth printheads can be fabricated so as to provide for a drop-on-demand ink ejection mechanism.

One form of detailed manufacturing process which can be used to fabricate monolithic ink jet printheads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps:

1. Using a double-sided polished wafer 60, complete a 0.5 micron, one poly, 2 metal CMOS process 61. This step is shown in FIG. 16. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. FIG. 15 is a key to representations of various materials in these manufacturing diagrams, and those of other cross-referenced ink jet configurations.

2. Etch the CMOS oxide layers down to silicon or second level metal using Mask 1. This mask defines the nozzle cavity and the edge of the chips. This step is shown in FIG. 16.

3. Deposit a thin layer (not shown) of a hydrophilic polymer, and treat the surface of this polymer for PTFE adherence.

4. Deposit 1.5 microns of polytetrafluoroethylene (PTFE) 62.

5. Etch the PTFE and CMOS oxide layers to second level metal using Mask 2. This mask defines the contact vias for the heater electrodes. This step is shown in FIG. 17.

6. Deposit and pattern 0.5 microns of gold 63 using a lift-off process using Mask 3. This mask defines the heater pattern. This step is shown in FIG. 18.

7. Deposit 1.5 microns of PTFE 64.

8. Etch 1 micron of PTFE using Mask 4. This mask defines the nozzle rim 65 and the rim at the edge 66 of the nozzle chamber. This step is shown in FIG. 19.

9. Etch both layers of PTFE and the thin hydrophilic layer down to silicon using Mask 5. This mask defines a gap 67 at inner edges of the actuators, and the edge of the chips. It also forms the mask for a subsequent crystallographic etch. This step is shown in FIG. 20.

10. Crystallographically etch the exposed silicon using KOH. This etch stops on <111> crystallographic planes 68, forming an inverted square pyramid with sidewall angles of 54.74 degrees. This step is shown in FIG. 21.

11. Back-etch through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 6. This mask defines the ink inlets 69 which are etched through the wafer. The wafer is also diced by this etch. This step is shown in FIG. 22.

12. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets 69 at the back of the wafer.

13. Connect the printheads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper.

14. Fill the completed print heads with ink 70 and test them. A filled nozzle is shown in FIG. 23.

The presently disclosed ink jet printing technology is potentially suited to a wide range of printing systems including: color and monochrome office printers, short run digital printers, high speed digital printers, offset press supplemental printers, low cost scanning printers high speed pagewidth printers, notebook computers with inbuilt pagewidth printers, portable color and monochrome printers, color and monochrome copiers, color and monochrome facsimile machines, combined printer, facsimile and copying machines, label printers, large format plotters, photograph copiers, printers for digital photographic “minilabs”, video printers, PHOTO CD (PHOTO CD is a registered trade mark of the Eastman Kodak Company) printers, portable printers for PDAs, wallpaper printers, indoor sign printers, billboard printers, fabric printers, camera printers and fault tolerant commercial printer arrays.

It would be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects to be illustrative and not restrictive.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Of course many different devices could be used. However, presently popular ink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal ink jet is power consumption. This is approximately 100 times that required for high speed, and stems from the energy-inefficient means of drop ejection. This involves the rapid boiling of water to produce a vapor bubble which expels the ink. Water has a very high heat capacity, and must be superheated in thermal ink jet applications. This leads to an efficiency of around 0.02%, from electricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric ink jet is size and cost. Piezoelectric crystals have a very small deflection at reasonable drive voltages, and therefore require a large area for each nozzle. Also, each piezoelectric actuator must be connected to its drive circuit on a separate substrate. This is not a significant problem at the current limit of around 300 nozzles per printhead, but is a major impediment to the fabrication of pagewidth printheads with 19,200 nozzles.

Ideally, the ink jet technologies used meet the stringent requirements of in-camera digital color printing and other high quality, high speed, low cost printing applications. To meet the requirements of digital photography, new ink jet technologies have been created. The target features include:

low power (less than 10 Watts)

High-resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the ink jet systems described below with differing levels of difficulty. Forty-five different ink jet technologies have been developed by the Assignee to give a wide range of choices for high volume manufacture. These technologies form part of separate applications assigned to the present Assignee as set out in the table below under the heading Cross References to Related Applications.

The ink jet designs shown here are suitable for a wide range of digital printing systems, from battery powered one-time use digital cameras, through to desktop and network printers, and through to commercial printing systems.

For ease of manufacture using standard process equipment, the printhead is designed to be a monolithic 0.5-micron CMOS chip with MEMS post processing. For color photographic applications, the printhead is 100 mm long, with a width which depends upon the ink jet type. The smallest printhead designed is IJ38, which is 0.35 mm wide, giving a chip area of 35 square mm. The printheads each contain 19,200 nozzles plus data and control circuitry.

Ink is supplied to the back of the printhead by injection molded plastic ink channels. The molding requires 50 micron features, which can be created using a lithographically micromachined insert in a standard injection molding tool. Ink flows through holes etched through the wafer to the nozzle chambers fabricated on the front surface of the wafer. The printhead is connected to the camera circuitry by tape automated bonding.

Tables of Drop-on-Demand Ink Jets

Eleven important characteristics of the fundamental operation of individual ink jet nozzles have been identified. These characteristics are largely orthogonal, and so can be elucidated as an eleven dimensional matrix. Most of the eleven axes of this matrix include entries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of ink jet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains 36.9 billion possible configurations of ink jet nozzle. While not all of the possible combinations result in a viable ink jet technology, many million configurations are viable. It is clearly impractical to elucidate all of the possible configurations. Instead, certain ink jet types have been investigated in detail. These are designated IJ01 to IJ45 above which matches the docket numbers in the table under the heading Cross References to Related Applications.

Other ink jet configurations can readily be derived from these forty-five examples by substituting alternative configurations along one or more of the 11 axes. Most of the IJ01 to IJ45 examples can be made into ink jet printheads with characteristics superior to any currently available ink jet technology.

Where there are prior art examples known to the inventor, one or more of these examples are listed in the examples column of the tables below. The IJ01 to IJ45 series are also listed in the examples column. In some cases, print technology may be listed more than once in a table, where it shares characteristics with more than one entry.

Suitable applications for the ink jet technologies include: Home printers, Office network printers, Short run digital printers, Commercial print systems, Fabric printers, Pocket printers, Internet WWW printers, Video printers, Medical imaging, Wide format printers, Notebook PC printers, Fax machines, Industrial printing systems, Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrix is set out in the following tables.

Description Advantages Disadvantages Examples ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Thermal An electro- Large force High power Canon bubble thermal heater generated Ink carrier Bubblejet heats the ink to Simple limited to water 1979 Endo above boiling construction Low efficiency et al GB point, No moving High patent transferring parts temperatures 2,007,162 significant heat Fast required Xerox to the aqueous operation High heater-in-pit ink. A bubble Small chip mechanical 1990 nucleates and area required stress Hawkins quickly forms, for actuator Unusual et al expelling the materials U.S. Pat No. ink. required 4,899,181 The efficiency Large drive Hewlett- of the process transistors Packard TIJ is low, with Cavitation 1982 Vaught typically less causes actuator et al than 0.05% of failure U.S. Pat No. the electrical Kogation 4,490,728 energy being reduces transformed bubble into kinetic formation energy of the Large print drop. heads are difficult to fabricate Piezo- A piezoelectric Low power Very large area Kyser et al electric crystal such as consumption required for U.S. Pat No. lead lanthanum Many ink actuator 3,946,398 zirconate (PZT) types can be Difficult to Zoltan is electrically used integrate with U.S. Pat No. activated, and Fast electronics 3,683,212 either expands, operation High voltage 1973 shears, or High drive Stemme bends to apply efficiency transistors U.S. Pat No. pressure to the required 3,747,120 ink, ejecting Full pagewidth Epson Stylus drops. print heads Tektronix to actuator size IJ04 Requires electrical poling in high field strengths during manufacture Requires electrical poling in high field strengths during manufacture Electro- An electric Low power Low maximum Seiko Epson, strictive field is used to consumption strain (approx. Usui et all JP activate Many ink 0.01%) 253401/96 electrostriction types can Large area IJ04 in relaxor be used required for materials such Low thermal actuator due to as lead expansion low strain lanthanum Electric field Response speed zirconate strength is marginal titanate (PLZT) required (~10 μs) or lead (approx. High voltage magnesium 3.5 V/μm) drive niobate (PMN). can be transistors generated required without Full pagewidth difficulty print heads Does not impractical due require to actuator size electrical poling Ferro- An electric Low power Difficult to IJ04 electric field is used to consumption integrate with induce a phase Many ink electronics transition types can Unusual between the be used materials such antiferroelectric Fast as PLZSnT are (AFE) and operation required ferroelectric (<1 μs) Actuators (FE) phase. Relatively require a Perovskite high large area materials such longitudinal as tin modified strain lead lanthanum High zirconate efficiency titanate Electric (PLZSnT) field exhibit large strength of strains of up to around 3 1% associated V/μm can with the AFE be readily to FE phase provided transition. Electro- Conductive Low power Difficult to IJ02, IJ04 static plates are consumption operate plates separated by a Many ink electrostatic compressible or types can devices in an fluid dielectric be used aqueous (usually air). Fast environment Upon operation The electro- application of a static actuator voltage, the will normally plates attract need to be each other and separated from displace ink, the ink causing drop Very large area ejection. The required to conductive achieve high plates may be forces in a comb or High voltage honeycomb drive structure, or transistors may stacked to be required increase the Full pagewidth surface area print heads are and therefore not competitive the force. due to actuator size Electro- A strong Low current High voltage 1989 Saito static electric field is consumption required et al, pull on applied to the Low May be U.S. Pat No. ink ink, whereupon temperature damaged by 4,799,068 electrostatic sparks due to 1989 Miura attraction air breakdown et al, accelerates the Required field U.S. Pat No. ink towards the strength 4,810,954 print medium. increases as the Tone-jet drop size decreases High voltage drive transistors required Electrostatic field attracts dust Permanent An electro- Low power Complex IJ07, IJ10 magnet magnet directly consumption fabrication electro- attracts a Many ink Permanent magnetic permanent types can magnetic magnet, be used material such displacing ink Fast as Neodymium and causing operation Iron Boron drop ejection. High (NdFeB) Rare earth efficiency required. magnets with a Easy High local field strength extension currents around 1 Tesla from single required can be used. nozzles to Copper Examples are: pagewidth metalization Samarium print heads should be used Cobalt (SaCo) for long and magnetic electro- materials in the migration neodymium lifetime and iron boron low resistivity family (NdFeB, Pigmented inks NdDyFeBNb, are usually NdDyFeB, etc) infeasible Operating temperature limited to the Curie temperature (around 540 K.) Soft A solenoid Low power Complex IJ01, IJ05, magnetic induced a consumption fabrication IJ08, IJ10, core magnetic field Many ink Materials not IJ12, IJ14, electro- in a soft types can usually present IJ15, IJ17 magnetic magnetic core be used in a CMOS fab or yoke Fast such as NiFe, fabricated from operation CoNiFe, or a ferrous High CoFe are material such efficiency required as electroplated Easy High local iron alloys such extension currents as CoNiFe [1], from single required CoFe, or NiFe nozzles to Copper alloys. pagewidth metalization Typically, the print heads should be used soft magnetic for long material is in electro- two parts, migration which are lifetime and normally held low resistivity apart by a Electroplating spring. is required When the High saturation solenoid is flux density is actuated, the required two parts (2.0-2.1 T is attract, achievable with displacing the CoNiFe [1]) ink. Lorenz The Lorenz Low power Force acts as a IJ06, IJ11, force force acting on consumption twisting motion IJ13, IJ16 a current Many ink Typically, only carrying wire types can a quarter of the in a magnetic be used solenoid length field is utilized. Fast provides force This allows the operation in a useful magnetic field High direction to be supplied efficiency High local externally to Easy currents the print head, extension required for example from single Copper with rare earth nozzles to metalization permanent pagewidth should be used magnets. print heads for long Only the electro- current migration carrying wire lifetime and need be low resistivity fabricated on Pigmented inks the print head, are usually simplifying infeasible materials requirements. Magneto- The actuator Many ink Force acts as a Fischenbeck, striction uses the giant types can twisting motion U.S. Pat No. magneto- be used Unusual 4,032,929 strictive effect Fast materials such IJ25 of materials operation as Terfenol-D such as Easy are required Terfenol-D (an extension High local alloy of from single currents terbium, nozzles to required dysprosium and pagewidth Copper iron developed print heads metalization at the Naval High force is should be used Ordnance available for long Laboratory, electro- hence migration Ter-Fe-NOL). lifetime and For best low resistivity efficiency, the Pre-stressing actuator should may be be pre-stressed required to approx. 8 MPa. Surface Ink under Low power Requires Silverbrook, tension positive consumption supplementary EP 0771 658 reduction pressure is held Simple force to effect A2 and in a nozzle by construction drop separation related surface tension. No unusual Requires patent The surface materials special ink applications tension of the required in surfactants ink is reduced fabrication Speed may be below the High limited by bubble efficiency surfactant threshold, Easy properties causing the ink extension to egress from from single the nozzle. nozzles to pagewidth print heads Viscosity The ink Simple Requires Silverbrook, reduction viscosity is construction supplementary EP 0771 658 locally reduced No unusual force to effect A2 and to select which materials drop separation related drops are to be required in Requires patent ejected. A fabrication special ink applications viscosity Easy viscosity reduction can extension properties be achieved from single High speed is electro- nozzles to difficult to thermally with pagewidth achieve most inks, but print heads Requires special inks can oscillating be engineered ink pressure for a 100:1 A high viscosity temperature reduction. difference (typically 80 degrees) is required Acoustic An acoustic Can operate Complex drive 1993 wave is without a circuitry Hadimioglu generated and nozzle plate Complex et al, EUP focussed upon fabrication 550,192 the drop Low 1993 Elrod ejection region. efficiency et al, EUP Poor control of 572,220 drop position Poor control of drop volume Thermo- An actuator Low power Efficient IJ03, IJ09, elastic which relies consumption aqueous IJ17, IJ18, bend upon Many ink operation IJ19, IJ20, actuator differential types can requires a IJ21, IJ22, thermal be used thermal IJ23, IJ24, expansion upon Simple insulator on the IJ27, IJ28, Joule heating planar hot side IJ29, IJ30, is used. fabrication Corrosion IJ31, IJ32, Small chip prevention can IJ33, IJ34, area required be difficult IJ35, IJ36, for each Pigmented inks IJ37, IJ38, actuator may be IJ39, IJ40, Fast infeasible, as IJ41 operation pigment High particles may efficiency jam the bend CMOS actuator compatible voltages and currents Standard MEMS processes can be used Easy extension from single nozzles to pagewidth print heads High CTE A material with High force Requires IJ09, IJ17, thermo- a very high can be special material IJ18, IJ20, elastic coefficient of generated (e.g. PTFE) IJ21, IJ22, actuator thermal Three Requires a IJ23, IJ24, expansion methods of PTFE IJ27, IJ28, (CTE) such as PTFE deposition IJ29, IJ30, polytetra- deposition process, which IJ31, IJ42, fluoroethylene are under is not yet IJ43, IJ44 (PTFE) is used. develop- standard in As high CTE ment: ULSI fabs materials are chemical PTFE usually non- vapor deposition conductive, a deposition cannot be heater (CVD), followed with fabricated from spin coating, high a conductive and temperature material is evaporation (above incorporated. A PTFE is a 350° C.) 50 μm long candidate processing PTFE bend for low Pigmented inks actuator with dielectric may be polysilicon constant infeasible, as heater and 15 insulation pigment mW power in- in ULSI particles may put can provide Very low jam the bend 180 μN force power actuator and 10 μm consumption deflection. Many ink Actuator types can be motions used include: Simple Bend planar Push fabrication Buckle Small chip Rotate area required for each actuator Fast operation High efficiency CMOS compatible voltages and currents Easy extension from single nozzles to pagewidth print heads Con- A polymer High force Requires IJ24 ductive with a high can be special polymer coefficient of generated materials thermo- thermal Very low development elastic expansion power (High CTE actuator (such as PTFE) consumption conductive is doped with Many ink polymer) conducting types can Requires a substances to be used PTFE increase its Simple deposition conductivity to planar process, which about 3 orders fabrication is not yet of magnitude Small chip standard in below that of area ULSI fabs copper. The required for PTFE conducting each actuator deposition polymer Fast cannot be expands when operation followed resistively High with high heated. efficiency temperature Examples of CMOS (above conducting compatible 350° C.) dopants voltages and processing include: currents Evaporation Carbon Easy and CVD nanotubes extension deposition Metal fibers from single techniques Conductive nozzles to cannot polymers such pagewidth be used as doped print heads Pigmented polythiophene inks may be Carbon infeasible, as granules pigment particles may jam the bend actuator Shape A shape High force is Fatigue limits IJ26 memory memory alloy available maximum alloy such as TiNi (stresses number of (also known as of hundreds cycles Nitinol - of MPa) Low strain Nickel Large strain (1%) is Titanium alloy is available required to developed at (more than extend fatigue the Naval 3%) resistance Ordnance High Cycle rate Laboratory) is corrosion limited by thermally resistance heat removal switched Simple Requires between its construction unusual weak Easy materials martensitic extension (TiNi) state and its from single The latent high stiffness nozzles to heat of austenitic state. pagewidth transformation The shape of print heads must be the actuator in Low voltage provided its martensitic operation High current state is operation deformed Requires pre- relative to stressing to the austenitic distort the shape. martensitic The shape state change causes ejection of a drop. Linear Linear Linear Requires IJ12 Magnetic magnetic Magnetic unusual semi- Actuator actuators actuators conductor include the can be materials such Linear constructed as soft Induction with high magnetic alloys Actuator (LIA), thrust, long (e.g. CoNiFe) Linear travel, and Some varieties Permanent high also require Magnet efficiency permanent Synchronous using planar magnetic Actuator semi- materials (LPMSA), conductor such as Linear fabrication Neodymium Reluctance techniques iron boron Synchronous Long (NdFeB) Actuator actuator Requires (LRSA), travel is complex Linear available multi-phase Switched Medium drive circuitry Reluctance force is High current Actuator available operation (LSRA), and Low voltage the Linear operation Stepper Actuator (LSA). BASIC OPERATION MODE Actuator This is the Simple Drop repetition Thermal directly simplest mode operation rate is usually ink jet pushes of operation: No external limited to Piezoelectric the ink actuator fields around 10 kHz. ink jet directly required However, this IJ01, IJ02, supplies Satellite is not IJ03, IJ04, sufficient drops can be fundamental to IJ05, IJ06, kinetic energy avoided if the method, but IJ07, IJ09, to expel the drop velocity is related to the IJ11, IJ12, drop. The drop is less than refill method IJ14, IJ16, must have a 4 m/s normally used IJ20, IJ22, sufficient Can be All of the drop IJ23, IJ24, velocity to efficient, kinetic energy IJ25, IJ26, overcome the depending must be IJ27, IJ28, surface tension. upon the provided by the IJ29, IJ30, actuator used actuator IJ31, IJ32, Satellite drops IJ33, IJ34, usually form if IJ35, IJ36, drop velocity is IJ37, IJ38, greater than IJ39, IJ40, 4.5 m/s IJ41, IJ42, IJ43, IJ44 Proximity The drops to be Very simple Requires close Silverbrook, printed are print head proximity EP 0771 658 selected by fabrication between the A2 and some manner can be used print head and related (e.g. thermally The drop the print media patent induced surface selection or transfer applications tension means does roller reduction of not need to May require pressurized provide the two print heads ink). Selected energy printing drops are required to alternate rows separated from separate the of the image the ink in the drop from Monolithic nozzle by the nozzle color print contact with heads are the print difficult medium or a transfer roller. Electro- The drops to be Very simple Requires very Silverbrook, static printed are print head high electro- EP 0771 658 pull on selected by fabrication static field A2 and ink some manner can be used Electrostatic related (e.g. thermally The drop field for small patent induced surface selection nozzle sizes is applications tension means does above air Tone-Jet reduction of not need to breakdown pressurized provide the Electrostatic ink). Selected energy field may drops are required to attract dust separated from separate the the ink in the drop from nozzle by a the nozzle strong electric field. Magnetic The drops to be Very simple Requires Silverbrook, pull on printed are print head magnetic ink EP 0771 658 ink selected by fabrication Ink colors other A2 and some manner can be used than black are related (e.g. thermally The drop difficult patent induced surface selection Requires very applications tension means does high magnetic reduction of not need fields pressurized to provide ink). Selected the energy drops are required to separated from separate the the ink in drop from the nozzle by the nozzle a strong magnetic field acting on the magnetic ink. Shutter The actuator High speed Moving parts IJ13, IJ17, moves a shutter (>50 kHz) are required IJ21 to block ink operation Requires ink flow to the can be pressure nozzle. The ink achieved due modulator pressure is to reduced Friction and pulsed at a refill time wear must be multiple of the Drop timing considered drop ejection can be very Stiction is frequency. accurate possible The actuator energy can be very low Shuttered The actuator Actuators Moving parts IJ08, IJ15, grill moves a shutter with small are required IJ18, IJ19 to block ink travel can Requires ink flow through a be used pressure grill to the Actuators modulator nozzle. The with small Friction and shutter force can be wear must be movement need used considered only be equal High speed Stiction is to the width of (>50 kHz) possible the grill holes. operation can be achieved Pulsed A pulsed Extremely Requires an IJ10 magnetic magnetic field low energy external pulsed pull on attracts an ‘ink operation is magnetic field ink pusher’ at the possible Requires pusher drop ejection No heat special frequency. An dissipation materials for actuator problems both the controls a actuator and catch, which the ink pusher prevents the Complex ink pusher construction from moving when a drop is not to be ejected. AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) None The actuator Simplicity of Drop ejection Most ink directly fires construction energy must be jets, the ink drop, Simplicity of supplied by including and there is no operation individual piezoelectric external field Small nozzle actuator and thermal or other physical size bubble. mechanism IJ01, IJ02, required. IJ03, IJ04, IJ05, IJ07, IJ09, IJ11, IJ12, IJ14, IJ20, IJ22, IJ23, IJ24, IJ25, IJ26, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ35, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Oscillating The ink Oscillating Requires Silverbrook, ink pressure ink pressure external ink EP 0771 658 pressure oscillates, can provide pressure A2 and (including providing much a refill pulse, oscillator related acoustic of the drop allowing Ink pressure patent stim- ejection higher phase and applications ulation) energy. The operating amplitude IJ08, IJ13, actuator selects speed must be IJ15, IJ17, which drops The carefully IJ18, IJ19, are to be fired actuators controlled IJ21 by selectively may operate Acoustic blocking or with much reflections enabling lower energy in the ink nozzles. The Acoustic chamber ink pressure lenses can must be oscillation may be used to designed be achieved by focus the for vibrating the sound on the print head, or nozzles preferably by an actuator in the ink supply. Media The print head Low power Precision Silverbrook, proximity is placed in High assembly EP 0771 658 close proximity accuracy required A2 and to the print Simple Paper fibers related medium. print head may cause patent Selected drops construction problems applications protrude from Cannot print the print head on rough further than substrates unselected drops, and contact the print medium. The drop soaks into the medium fast enough to cause drop separation. Transfer Drops are High Bulky Silverbrook, roller printed to a accuracy Expensive EP 0771 658 transfer roller Wide range Complex A2 and instead of of print construction related straight to the substrates patent print medium. can be used applications A transfer Ink can be Tektronix roller can also dried on hot melt be used for the transfer piezoelectric proximity drop roller ink jet separation. Any of the IJ series Electro- An electric Low power Field strength Silverbrook, static field is used to Simple required for EP 0771 658 accelerate print head separation of A2 and selected drops construction small drops is related towards the near or above patent print medium. air breakdown applications Tone-Jet Direct A magnetic Low power Requires Silverbrook, magnetic field is used to Simple magnetic ink EP 0771 658 field accelerate print head Requires strong A2 and selected drops construction magnetic field related of magnetic ink patent towards the applications print medium. Cross The print head Does not Requires IJ06, IJ16 magnetic is placed in a require external field constant magnetic magnet magnetic field. materials Current The Lorenz to be densities may force in a integrated be high, current in the resulting in carrying wire print head electro- is used to move manu- migration the actuator. facturing problems process Pulsed A pulsed Very low Complex IJ10 magnetic magnetic field power print head field is used to operation is construction cyclically possible Magnetic attract a Small print materials paddle, which head size required in pushes on the print head ink. A small actuator moves a catch, which selectively prevents the paddle from moving. ACTUATOR AMPLIFICATION OR MODIFICATION METHOD None No actuator Operational Many actuator Thermal mechanical simplicity mechanisms Bubble amplification have Ink jet is used. The insufficient IJ01, IJ02, actuator travel, or IJ06, IJ07, directly drives insufficient IJ16, IJ25, the drop force, to IJ26 ejection efficiently process. drive the drop ejection process Differ- An actuator Provides High stresses Piezoelectric ential material greater are involved IJ03, IJ09, expansion expands more travel in Care must be IJ17, IJ18, bend on one side a reduced taken that the IJ19, IJ20, actuator than on the print head materials do IJ21, IJ22, other. The area not delaminate IJ23, IJ24, expansion may Residual bend IJ27, IJ29, be thermal, resulting from IJ30, IJ31, piezoelectric, high IJ32, IJ33, magneto- temperature or IJ34, IJ35, strictive, or high stress IJ36, IJ37, other during IJ38, IJ39, mechanism. formation IJ42, IJ43, The bend IJ44 actuator converts a high force low travel actuator mechanism to high travel, lower force mechanism. Transient A trilayer bend Very good High stresses IJ40, IJ41 bend actuator where temperature are involved actuator the two outside stability Care must be layers are High speed, taken that the identical. This as a new materials do cancels bend drop can be not delaminate due to ambient fired before temperature heat and residual dissipates stress. The Cancels actuator only residual responds to stress of transient formation heating of one side or the other. Reverse The actuator Better Fabrication IJ05, IJ11 spring loads a spring. coupling to complexity When the the ink High stress in actuator is the spring turned off, the spring releases. This can reverse the force/distance curve of the actuator to make it compatible with the force/time requirements of the drop ejection. Actuator A series of thin Increased Increased Some stack actuators are travel fabrication piezoelectric stacked. This Reduced complexity ink jets can be drive Increased IJ04 appropriate voltage possibility of where actuators short circuits require high due to pinholes electric field strength, such as electrostatic and piezo- electric actuators. Multiple Multiple Increases Actuator forces IJ12, IJ13, actuators smaller the force may not add IJ18, IJ20, actuators available linearly, IJ22, IJ28, are used from an reducing IJ42, IJ43 simultaneously actuator efficiency to move the Multiple ink. Each actuators actuator need can be provide only a positioned portion of the to control force required. ink flow accurately Linear A linear spring Matches low Requires print IJ15 Spring is used to travel head area for transform a actuator with the spring motion with higher travel small travel requirements and high force Non-contact into a longer method of travel, lower motion force motion. trans- formation Coiled A bend Increases Generally IJ17, IJ21, actuator actuator is travel restricted to IJ34, IJ35 coiled to Reduces chip planar imple- provide greater area mentations due travel in a Planar to extreme reduced chip implemen- fabrication area. tations are difficulty relatively in other easy to orientations. fabricate. Flexure A bend Simple Care must be IJ10, IJ19, bend actuator has a means of taken not to IJ33 actuator small region increasing exceed the near the fixture travel of elastic limit in point, which a bend the flexure area flexes much actuator Stress more readily distribution is than the very uneven remainder of Difficult to the actuator. accurately The actuator model with flexing is finite element effectively analysis converted from an even coiling to an angular bend, resulting in greater travel of the actuator tip. Catch The actuator Very low Complex IJ10 controls a small actuator construction catch. The energy Requires catch either Very small external force enables or actuator Unsuitable for disables size pigmented inks movement of an ink pusher that is controlled in a bulk manner. Gears Gears can be Low force, Moving parts IJ13 used to low travel are required increase travel actuators can Several at the expense be used actuator cycles of duration. Can be are required Circular gears, fabricated More complex rack and using drive pinion, standard electronics ratchets, and surface Complex other gearing MEMS construction methods can be processes Friction, used. friction, and wear are possible Buckle A buckle plate Very fast Must stay S. Hirata plate can be used to movement within elastic et al, “An change a slow achievable limits of the Ink-jet Head actuator into a materials for Using fast motion. It long device life Diaphragm can also High stresses Micro- convert a high involved actuator”, force, low Generally high Proc. IEEE travel actuator power MEMS, into a high requirement Feb. 1996, travel, medium pp 418-423. force motion. IJ18, IJ27 Tapered A tapered Linearizes Complex IJ14 magnetic magnetic pole the magnetic construction pole can increase force/ travel at the distance expense of curve force. Lever A lever and Matches low High stress IJ32, IJ36, fulcrum is used travel around the IJ37 to transform a actuator with fulcrum motion with higher travel small travel requirements and high force Fulcrum area into a motion has no with longer linear travel and movement, lower force. and can be The lever can used for also reverse the a fluid seal direction of travel. Rotary The actuator is High Complex IJ28 impeller connected to a mechanical construction rotary impeller. advantage Unsuitable for A small The ratio of pigmented inks angular force to deflection of travel of the the actuator actuator can results in a be matched rotation of the to the nozzle impeller vanes, requirements which push the by varying ink against the number stationary of impeller vanes and out vanes of the nozzle. Acoustic A refractive or No moving Large area 1993 lens diffractive (e.g. parts required Hadimioglu zone plate) Only relevant et al, EUP acoustic lens is for acoustic ink 550,192 used to jets 1993 Elrod concentrate et al, EUP sound waves. 572,220 Sharp A sharp point Simple Difficult to Tone-jet conductive is used to construction fabricate using point concentrate an standard VLSI electrostatic processes for a field. surface ejecting inkjet Only relevant for electrostatic ink jets ACTUATOR MOTION Volume The volume of Simple High energy is Hewlett- expansion the actuator construction typically Packard changes, in the case required to Thermal pushing the of thermal achieve volume Ink jet ink in all ink jet expansion. This Canon directions. leads to Bubblejet thermal stress, cavitation, and kogation in thermal ink jet implemen- tations Linear, The actuator Efficient High IJ01, IJ02, normal moves in a coupling to fabrication IJ04, IJ07, to chip direction ink drops complexity IJ11, IJ14 surface normal to the ejected may be print head normal to required to surface. The the surface achieve nozzle is perpendicular typically in motion the line of movement. Parallel The actuator Suitable for Fabrication IJ12, IJ13, to chip moves parallel planar complexity IJ15, IJ33, surface to the print fabrication Friction IJ34, IJ35, head surface. Stiction IJ36 Drop ejection may still be normal to the surface. Membrane An actuator The effective Fabrication 1982 push with a high area of the complexity Howkins force but small actuator Actuator size U.S. Pat No. area is used to becomes the Difficulty of 4,459,601 push a stiff membrane integration in a membrane that area VLSI process is in contact with the ink. Rotary The actuator Rotary levers Device IJ05, IJ08, causes the may be used complexity IJ13, IJ28 rotation of to increase May have some element, travel friction at a such a grill Small chip pivot point or impeller area requirements Bend The actuator A very small Requires the 1970 Kyser bends when change in actuator to be et al energized. This dimensions made from at U.S. Pat No. may be due to can be least two 3,946,398 differential converted to distinct layers, 1973 thermal a large or to have a Stemme expansion, motion. thermal U.S. Pat No. piezoelectric difference 3,747,120 expansion, across the IJ03, IJ09, magneto- actuator IJ10, IJ19, striction, or IJ23, IJ24, other form of IJ25, IJ29, relative IJ30, IJ31, dimensional IJ33, IJ34, change. IJ35 Swivel The actuator Allows Inefficient IJ06 swivels around operation coupling to the a central pivot, where the ink motion This motion is net linear suitable where force on there are the paddle opposite forces is zero applied to Small chip opposite sides area of the paddle, requirements e.g. Lorenz force. Straighten The actuator is Can be used Requires IJ26, IJ32 normally bent, with shape careful balance and straightens memory of stresses to when alloys ensure that the energized. where the quiescent bend austenitic is accurate phase is planar Double The actuator One actuator Difficult to IJ36, IJ37, bend bends in one can be used make the drops IJ38 direction when to power two ejected by both one element is nozzles. bend directions energized, and Reduced identical. bends the other chip size. A small way when Not sensitive efficiency loss another to ambient compared to element is temperature equivalent energized. single bend actuators. Shear Energizing the Can increase Not readily 1985 actuator causes the effective applicable to Fishbeck a shear motion travel of other actuator U.S. Pat No. in the actuator piezoelectric mechanisms 4,584,590 material. actuators Radial The actuator Relatively High force 1970 Zoltan con- squeezes an easy to required U.S. Pat No. striction ink reservoir, fabricate Inefficient 3,683,212 forcing ink single Difficult to from a nozzles integrate with constricted from glass VLSI nozzle. tubing as processes macroscopic structures Coil/ A coiled Easy to Difficult to IJ17, IJ21, uncoil actuator uncoils fabricate fabricate for IJ34, IJ35 or coils more as a planar non-planar tightly. The VLSI devices motion of the process Poor out-of- free end of the Small area plane stiffness actuator ejects required, the ink. therefore low cost Bow The actuator Can increase Maximum IJ16, IJ18, bows (or the speed travel is IJ27 buckles) in the of travel constrained middle when Mechan- High force energized. ically required rigid Push-Pull Two actuators The structure Not readily IJ18 control a is pinned at suitable for ink shutter. One both ends, jets which actuator pulls so has a high directly push the shutter, out-of-plane the ink and the other rigidity pushes it. Curl A set of Good fluid Design IJ20, IJ42 inwards actuators curl flow to the complexity inwards to region reduce the behind the volume of ink actuator that they increases enclose. efficiency Curl A set of Relatively Relatively large IJ43 outwards actuators curl simple chip area outwards, construction pressurizing ink in a chamber surrounding the actuators, and expelling ink from a nozzle in the chamber. Iris Multiple vanes High High IJ22 enclose a efficiency fabrication volume of ink. Small chip complexity These area Not suitable for simultaneously pigmented inks rotate, reducing the volume between the vanes. Acoustic The actuator The actuator Large area 1993 vibration vibrates at a can be required for Hadimioglu high frequency. physically efficient et al, EUP distant operation at 550,192 from the ink useful 1993 Elrod frequencies et al, EUP Acoustic 572,220 coupling and crosstalk Complex drive circuitry Poor control of drop volume and position None In various ink No moving Various other Silverbrook, jet designs the parts tradeoffs are EP 0771 658 actuator does required to A2 and not move. eliminate related moving parts patent applications Tone-jet NOZZLE REFILL METHOD Surface This is the Fabrication Low speed Thermal tension normal way simplicity Surface tension ink jet that ink jets are Operational force relatively Piezoelectric refilled. After simplicity small compared inkjet the actuator is to actuator IJ01-IJ07, energized, it force IJ10-IJ14, typically Long refill IJ16, IJ20, returns rapidly time usually IJ22-IJ45 to its normal dominates the position. This total repetition rapid return rate sucks in air through the nozzle opening. The ink surface tension at the nozzle then exerts a small force restoring the meniscus to a minimum area. This force refills the nozzle. Shuttered Ink to the High speed Requires IJ08, IJ13, oscillating nozzle chamber Low actuator common ink IJ15, IJ17, ink is provided at energy, as pressure IJ18, IJ19, pressure a pressure that the actuator oscillator IJ21 oscillates at need only May not be twice the drop open or close suitable for ejection the shutter, pigmented inks frequency. instead of When a drop is ejecting the to be ejected, ink drop the shutter is opened for 3 half cycles: drop ejection, actuator return, and refill. The shutter is then closed to prevent the nozzle chamber emptying during the next negative pressure cycle. Refill After the main High speed, Requires two IJ09 actuator actuator has as the independent ejected a drop a nozzle is actuators per second (refill) actively nozzle actuator is refilled energized. The refill actuator pushes ink into the nozzle chamber. The refill actuator returns slowly, to prevent its return from emptying the chamber again. Positive The ink is held High refill Surface spill Silverbrook, ink a slight positive rate, must be EP 0771 658 pressure pressure. After therefore a prevented A2 and the ink drop is high drop Highly hydro- related ejected, the repetition phobic print patent nozzle chamber rate is head surfaces applications fills quickly as possible are required Alternative surface tension for:, and ink IJ01-IJ07, pressure both IJ10-IJ14, operate to refill IJ16, IJ20, the nozzle. IJ22-IJ45 METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Long inlet The ink inlet Design Restricts refill Thermal channel channel to the simplicity rate ink jet nozzle chamber Operational May result in a Piezoelectric is made long simplicity relatively large ink jet and relatively Reduces chip area IJ42, IJ43 narrow, relying crosstalk Only partially on viscous drag effective to reduce inlet back-flow. Positive The ink is Drop Requires a Silverbrook, ink under a selection and method (such EP 0771 658 pressure positive separation as a nozzle rim A2 and pressure, so forces or effective related that in the can be hydro- patent quiescent state reduced phobizing, or applications some of the ink Fast refill both) to Possible drop already time prevent operation protrudes from flooding of the of the the nozzle. ejection surface following: This reduces of the print IJ01-IJ07, the pressure in head. IJ09-IJ12, the nozzle IJ14, IJ16, chamber which IJ20, IJ22, is required to IJ23-IJ34, eject a certain IJ36-IJ41, volume of ink. IJ44 The reduction in chamber pressure results in a reduction in ink pushed out through the inlet. Baffle One or more The refill Design TIP Thermal baffles are rate is not complexity Ink Jet placed in the as restricted May increase Tektronix inlet ink flow. as the long fabrication piezoelectric When the inlet method. complexity ink jet actuator is Reduces (e.g. Tektronix energized, the crosstalk hot melt rapid ink Piezoelectric movement print heads). creates eddies which restrict the flow through the inlet. The slower refill process is unrestricted, and does not result in eddies. Flexible In this method Significantly Not applicable Canon flap recently reduces to most ink jet restricts disclosed by back-flow configurations inlet Canon, the for edge- Increased expanding shooter fabrication actuator thermal complexity (bubble) pushes ink jet Inelastic on a flexible devices deformation of flap that polymer flap restricts the results in creep inlet. over extended use Inlet A filter is Additional Restricts refill IJ04, IJ12, filter located advantage rate IJ24, IJ27, between the ink of ink May result IJ29, IJ30 inlet and the filtration in complex nozzle Ink filter construction chamber. The may be filter has a fabricated multitude of with no small holes or additional slots, process restricting ink steps flow. The filter also removes particles which may block the nozzle. Small inlet The ink inlet Design Restricts refill IJ02, IJ37, compared channel to the simplicity rate IJ44 to nozzle nozzle chamber May result in a has a relatively large substantially chip area smaller cross Only partially section than effective that of the nozzle, resulting in easier ink egress out of the nozzle than out of the inlet. Inlet A secondary Increases Requires IJ09 shutter actuator speed of separate refill controls the the ink-jet actuator and position of a print head drive circuit shutter, closing operation off the ink inlet when the main actuator is energized. The inlet The method Back-flow Requires IJ01, IJ03, is located avoids the problem is careful design IJ05, IJ06, behind problem of eliminated to minimize the IJ07, IJ10, the ink- inlet back-flow negative IJ11, IJ14, pushing by arranging pressure behind IJ16, IJ22, surface the ink-pushing the paddle IJ23, IJ25, surface of the IJ28, IJ31, actuator IJ32, IJ33, between the IJ34, IJ35, inlet and the IJ36, IJ39, nozzle. IJ40, IJ41 Part of the The actuator Significant Small increase IJ07, IJ20, actuator and a wall of reductions in fabrication IJ26, IJ38 moves to the ink in back- complexity shut off chamber are flow can be the inlet arranged so achieved that the motion Compact of the actuator designs closes off the possible inlet. Nozzle In some Ink None related to Silverbrook, actuator configurations back-flow ink back-flow EP 0771 658 does not of ink jet, there problem is on actuation A2 and result is no expansion eliminated related in ink or movement patent back-flow of an actuator applications which may Valve-jet cause ink Tone-jet back-flow through the inlet. NOZZLE CLEARING METHOD Normal All of the No added May not be Most ink nozzle nozzles are complexity sufficient to jet systems firing fired on the displace dried IJ01, IJ02, periodically, print head ink IJ03, IJ04, before the ink IJ05, IJ06, has a chance to IJ07, IJ09, dry. When not IJ10, IJ11, in use the IJ12, IJ14, nozzles are IJ16, IJ20, sealed (capped) IJ22, IJ23, against air. IJ24, IJ25, The nozzle IJ26, IJ27, firing is IJ28, IJ29, usually IJ30, IJ31, performed IJ32, IJ33, during a special IJ34, IJ36, clearing cycle, IJ37, IJ38, after first IJ39, IJ40, moving the IJ41, IJ42, print head to IJ43, IJ44, a cleaning IJ45 station. Extra In systems Can be Requires higher Silverbrook, power which heat the highly drive voltage EP 0771 658 to ink ink, but do not effective for clearing A2 and heater boil it under if the May require related normal heater is larger drive patent situations, adjacent to transistors applications nozzle clearing the nozzle can be achieved by overpowering the heater and boiling ink at the nozzle. Rapid The actuator is Does not Effectiveness May be succession fired in rapid require depends used with: of actuator succession. extra drive substantially IJ01, IJ02, pulses In some circuits upon the IJ03, IJ04, configurations, on the configuration IJ05, IJ06, this may cause print head of the ink jet IJ07, IJ09, heat build-up at Can be nozzle IJ10, IJ11, the nozzle readily IJ14, IJ16, which boils the controlled IJ20, IJ22, ink, clearing and IJ23, IJ24, the nozzle. initiated IJ25, IJ27, In other by digital IJ28, IJ29, situations, it logic IJ30, IJ31, may cause IJ32, IJ33, sufficient IJ34, IJ36, vibrations to IJ37, IJ38, dislodge IJ39, IJ40, clogged IJ41, IJ42, nozzles. IJ43, IJ44, IJ45 Extra Where an A simple Not suitable May be power to actuator is solution where there is used with: ink not normally where a hard limit to IJ03, IJ09, pushing driven to the applicable actuator IJ16, IJ20, actuator limit of its movement IJ23, IJ24, motion, nozzle IJ25, IJ27, clearing may IJ29, IJ30, be assisted by IJ31, IJ32, providing an IJ39, IJ40, enhanced drive IJ41, IJ42, signal to the IJ43, IJ44, actuator. IJ45 Acoustic An ultrasonic A high High IJ08, IJ13, resonance wave is applied nozzle implementation IJ15, IJ17, to the ink clearing cost if system IJ18, IJ19, chamber. This capability does not IJ21 wave is of an can be already include appropriate achieved an acoustic amplitude and May be actuator frequency to implemented cause sufficient at very force at the low cost nozzle to clear in systems blockages. This which is easiest to already achieve if the include ultrasonic wave acoustic is at a resonant actuators frequency of the ink cavity. Nozzle A micro- Can clear Accurate Silverbrook, clearing fabricated plate severely mechanical EP 0771 658 plate is pushed clogged alignment is A2 and against the nozzles required related nozzles. The Moving parts patent plate has a post are required applications for every There is risk of nozzle. A post damage to the moves through nozzles each nozzle, Accurate displacing fabrication dried ink. is required Ink The pressure of May be Requires May be pressure the ink is effective pressure pump used with pulse temporarily where or other all IJ increased so other pressure series that ink streams methods actuator ink jets from all of the cannot Expensive nozzles. This be used Wasteful of ink may be used in conjunction with actuator energizing. Print A flexible Effective Difficult to use Many head ‘blade’ is for planar if print head ink jet wiper wiped across print head surface is non- systems the print head surfaces planar or very surface. The Low cost fragile blade is usually Requires fabricated from mechanical a flexible parts polymer, e.g. Blade can wear rubber or out in high synthetic volume print elastomer. systems Separate A separate Can be Fabrication Can be used ink heater is effective complexity with many IJ boiling provided at the where other series ink heater nozzle although nozzle jets the normal clearing drop ejection methods mechanism cannot does not be used require it. The Can be heaters do not implemented require at no individual drive additional circuits, as cost in many nozzles some ink can be cleared jet con- simultaneously, figurations and no imaging is required. NOZZLE PLATE CONSTRUCTION Electro- A nozzle plate Fabrication High Hewlett formed is separately simplicity temperatures Packard nickel fabricated from and pressures Thermal electroformed are required to Ink jet nickel, and bond nozzle bonded to the plate print head chip. Minimum thickness constraints Differential thermal expansion Laser Individual No masks Each hole must Canon ablated or nozzle holes required be individually Bubblejet drilled are ablated by Can be formed 1988 Sercel polymer an intense UV quite fast Special et al., SPIE, laser in a Some equipment Vol. 998 nozzle plate, control required Excimer which is over Slow where Beam typically a nozzle there are many Applications, polymer such profile is thousands of pp. 76-83 as polyimide or possible nozzles per 1993 polysulphone Equipment print head Watanabe required is May produce et al., relatively thin burrs at U.S. Pat No. low cost exit holes 5,208,604 Silicon A separate High Two part K. Bean, micro- nozzle plate is accuracy is construction IEEE Trans- machined micromachined attainable High cost actions on from single Requires Electron crystal silicon, precision Devices, and bonded to alignment Vol. ED-25, the print head Nozzles may No. 10, wafer. be clogged by 1978, pp adhesive 1185-1195 Xerox 1990 Hawkins et al., U.S. Pat No. 4,899,181 Glass Fine glass No Very small 1970 Zoltan capillaries capillaries are expensive nozzle sizes are U.S. Pat No. drawn from equipment difficult to 3,683,212 glass tubing. required form This method Simple Not suited has been used to make for mass for making single production individual nozzles nozzles, but is difficult to use for bulk manufacturing of print heads with thousands of nozzles. Mono- The nozzle High Requires Silverbrook, lithic, plate is accuracy sacrificial layer EP 0771 658 surface deposited as a (<1 μm) under the A2 and micro- layer using Monolithic nozzle plate to related machined standard VLSI Low cost form the nozzle patent using deposition Existing chamber applications VLSI techniques. processes Surface may be IJ01, IJ02, litho- Nozzles are can be fragile to the IJ04, IJ11, graphic etched in the used touch IJ12, IJ17, processes nozzle plate IJ18, IJ20, using VLSI IJ22, IJ24, lithography and IJ27, IJ28, etching. IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Mono- The nozzle High Requires long IJ03, IJ05, lithic, plate is a accuracy etch times IJ06, IJ07, etched buried etch (<1 μm) Requires a IJ08, IJ09, through stop in the Monolithic support wafer IJ10, IJ13, substrate wafer. Nozzle Low cost IJ14, IJ15, chambers are No IJ16, IJ19, etched in the differential IJ21, IJ23, front of the expansion IJ25, IJ26 wafer, and the wafer is thinned from the backside. Nozzles are then etched in the etch stop layer. No nozzle Various No nozzles Difficult to Ricoh 1995 plate methods have to become control drop Sekiya been tried to clogged position et al USP eliminate the accurately U.S. Pat No. nozzles Crosstalk 5,412,413 entirely, to problems 1993 prevent nozzle Hadimioglu clogging. et al EUP These include 550,192 thermal bubble 1993 Elrod mechanisms et al EUP and acoustic 572,220 lens mechanisms Trough Each drop Reduced Drop firing IJ35 ejector has a manu- direction is trough through facturing sensitive to which a paddle complexity wicking. moves. There Monolithic is no nozzle plate. Nozzle slit The elimination No nozzles Difficult to 1989 Saito instead of of nozzle holes to become control drop et al individual and replace- clogged position U.S. Pat No. nozzles ment by a slit accurately 4,799,068 encompassing Crosstalk many actuator problems positions reduces nozzle clogging, but increases crosstalk due to ink surface waves DROP EJECTION DIRECTION Edge Ink flow is Simple Nozzles limited Canon (‘edge along the construction to edge Bubblejet shooter’) surface of the No silicon High resolution 1979 Endo chip, and ink etching is difficult et al GB drops are required Fast color patent ejected from Good heat printing 2,007,162 the chip edge. sinking requires one Xerox via substrate print head per heater-in-pit Mechanic- color 1990 ally strong Hawkins Ease of et al chip U.S. Pat No. handing 4,899,181 Tone-jet Surface Ink flow is No bulk Maximum ink Hewlett- (‘roof along the silicon flow is severely Packard TIJ shooter’) surface of the etching restricted 1982 Vaught chip, and ink required et al drops are Silicon can U.S. Pat No. ejected from make an 4,490,728 the chip effective IJ02, IJ11, surface, normal heat sink IJ12, IJ20, to the plane of Mechanical IJ22 the chip. strength Through Ink flow is High ink Requires bulk Silverbrook, chip, through the flow silicon etching EP 0771 658 forward chip, and ink Suitable for A2 and (‘up drops are pagewidth related shooter’) ejected from print heads patent the front High nozzle applications surface of packing IJ04, IJ17, the chip. density IJ18, IJ24, therefore IJ27-IJ45 low manu- facturing cost Through Ink flow is High ink Requires wafer IJ01, IJ03, chip, through the flow thinning IJ05, IJ06, reverse chip, and ink Suitable for Requires IJ07, IJ08, (‘down drops are pagewidth special IJ09, IJ10, shooter’) ejected from print heads handling during IJ13, IJ14, the rear High nozzle manufacture IJ15, IJ16, surface of packing IJ19, IJ21, the chip. density IJ23, IJ25, therefore IJ26 low manu- facturing cost Through Ink flow is Suitable for Pagewidth print Epson actuator through the piezoelectric heads require Stylus actuator, which print heads several Tektronix is not thousand hot melt fabricated as connections to piezoelectric part of the drive circuits ink jets same substrate Cannot be as the drive manufactured transistors. in standard CMOS fabs Complex assembly required INK TYPE Aqueous, Water based Environ- Slow drying Most dye ink which mentally Corrosive existing typically friendly Bleeds on ink jets contains: water, No odor paper All IJ series dye, surfactant, May strike- ink jets humectant, and through Silverbrook, biocide. Cockles paper EP 0771 658 Modern ink A2 and dyes have high related water-fastness, patent light fastness applications Aqueous, Water based Environ- Slow drying IJ02, IJ04, pigment ink which mentally Corrosive IJ21, IJ26, typically friendly Pigment may IJ27, IJ30 contains: water, No odor clog nozzles Silverbrook, pigment, Reduced Pigment may EP 0771 658 surfactant, bleed clog actuator A2 and humectant, and Reduced mechanisms related biocide. wicking Cockles paper patent Pigments have Reduced applications an advantage in strike- Piezoelectric reduced bleed, through inkjets wicking and Thermal strikethrough. ink jets (with significant restrictions) Methyl MEK is a Very fast Odorous All IJ series Ethyl highly volatile drying Flammable ink jets Ketone solvent used Prints on (MEK) for industrial various printing on substrates difficult such as surfaces such metals and as aluminum plastics cans. Alcohol Alcohol based Fast drying Slight odor All IJ series (ethanol, inks can be Operates at Flammable ink jets 2-butanol, used where the subfreezing and printer must temperatures others) operate at Reduced temperatures paper cockle below the Low cost freezing point of water. An example of this is in-camera consumer photographic printing. Phase The ink is solid No drying High viscosity Tektronix change at room time - ink Printed ink hot melt (hot melt) temperature, instantly typically has a piezoelectric and is melted freezes on ‘waxy’ feel ink jets in the print the print Printed pages 1989 Nowak head before medium may ‘block’ U.S. Pat No. jetting. Hot Almost Ink temperature 4,820,346 melt inks are any print may be above All IJ series usually wax medium can the curie point ink jets based, with a be used of permanent melting point No paper magnets around 80° C. cockle Ink heaters After jetting occurs consume power the ink freezes No wicking Long warm-up almost instantly occurs time upon No bleed contacting the occurs print medium No strike- or a transfer through roller. occurs Oil Oil based inks High High viscosity: All IJ series are extensively solubility this is a ink jets used in offset medium for significant printing. some dyes limitation for They have Does not use in ink jets, advantages in cockle which usually improved paper require a low characteristics Does not viscosity. Some on paper wick short chain and (especially no through multi-branched wicking or paper oils have a cockle). Oil sufficiently soluble dies low viscosity. and pigments Slow drying are required. Micro- A micro- Stops ink Viscosity All IJ series emulsion emulsion is a bleed higher than ink jets stable, self High dye water forming solubility Cost is slightly emulsion of oil, Water, oil, higher than water, and and water based ink surfactant. The amphiphilic High surfactant characteristic soluble concentration drop size is dies can required less than be used (around 5%) 100 nm, and is Can determined by stabilize the preferred pigment curvature of suspensions the surfactant. 

1. A fluid ejection chip that comprises: a substrate; and a plurality of nozzle arrangements positioned on the substrate, each nozzle arrangement comprising: a nozzle chamber defining structure which defines a nozzle chamber and which includes a wall in which a fluid ejection port is defined; and a series of thermal bend actuators arranged to extend from the nozzle chamber to the fluid ejection port so as to define said wall between the nozzle chamber and fluid ejection port; wherein, the thermal bend actuators are configured to be activated on receipt of an electrical signal so as to all be displaced toward the substrate in order to reduce the volume of the nozzle chamber and be deactivated upon removal of the electrical signal so as to all be displaced back to their original positions in order to restore the volume of the nozzle chamber, thereby causing ejection of fluid through the fluid ejection port.
 2. The fluid ejection chip of claim 1, in which each thermal bend actuator includes an actuating portion and a paddle positioned on the actuating portion, the actuating portion being anchored to the substrate and being displaceable on receipt of an electrical signal to displace the paddle, in turn, the paddles and the wall being substantially coplanar and the actuating portions being configured so that, upon receipt of said electrical signal, the actuating portions displace the paddles into the nozzle chamber to reduce a volume of the nozzle chamber, thereby ejecting fluid from the fluid ejection port.
 3. The fluid ejection chip of claim 2 in which a periphery of each paddle is shaped to define a fluidic seal when the nozzle chamber is filled with fluid. 